Telephone-transmitter



(No Model.)

D. N. ROWAN. TELEPHONE TRANSMITTER.

Patented Nov. 17, 1896.

. UNITED STATES PATENT OFFICE.

DAVID NOBLE ROIVAN, OF IRVINGTON, NE\V YORK.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 571,399, dated November1'7, 1896.

' Application fil d December 10,1895. Serial No. 571,701. (No model.)

To all whom it may concern:

Be it known that I, DAVID NOBLE ROWAN, a citizen of the United States,residing at Irvington, county of Westchestcr, State of New York, haveinvented a certain new and useful Improvement in Telephone-Transmitters,of which the following is a full, clear, concise, and exact description,reference being had to the accompanying drawings, forming a part of thisspecification.

My invention relates to telephone-transmitters with two electrodes,between which granulated or globular particles of conducting material isused to vary the electrical resistance, and adapted to short or longdistance service.

I prefer to construct my transmitters by having a solid electrode in thercar,with nonconducting shelves attached to its face,witl1 granular orglobular conducting material suspended on the shelves between theelectrodes.

My invention consists in the combination of fiexible-non-conductingshelves with sufficient granular or globular conducting materialsuspended on the shelves between the electrodes to produce the requiredvarying resistance, first, in combination with a single diaphragm incontact with the shelves and the granular or globular conductingmaterial regulated by a pressure device; second, in combination with amovable inner diaphragm in contact with the shelves and the granular orglobular conducting material,with a fixed outer diaphragm, with a spacebetween the diaphraglns, with a pressure device, for in stance, a screwand nut, for regulating the pressure of the inner diaphragm against theshelves and the granular or globular conducting material. These shelvesmay be madein various ways, but I have produced the best results withand prefer to use shelves, horizontal or circular, made of thin stripsof mica or celluloid, as shown in my illustrations, which I can securelyattach at any required angle to the face of the rear electrode. I preferthe use of mica forthe shelves because it is practically indestructible,not affected by the weather, and does not deteriorate by age, is notattacked by parasites, and possesses in the highest degree the qualityof resiliency and responds to the vibrations of the diaphragm, and thegranules are by each continuously moved by or agitated by the sameprocess. It is impossible for the granules to pack on the shelves oragainst the electrodes.

I11 adjusting the workings of the transmitter when a single diaphragm isused I place the front electrode so that it presses against theprojecting edges of theshelves, which keeps the granules fromoverflowing from one shelf to another or into the case and brings thegranules in contact with the front electrode above the line of shelves.The ends of the shelves constructed to be horizontal when used areclosed at each end by non-conducting material, and the circular shelvesare continuous. Each shelf securely holdsthe granules therein placed..Any adj ustment needed to produce the more perfect results can be madeby moving the front electrode forward, pressing the flexible shelves andthe granules, or drawingitback to relieve the pressure when the rearelectrode is stationary, as, for instance, by a screw and nut, or bymovingthe rear electrode to which the shelves are attached up to or backfrom the front electrode when the diaphragm is stationary. Another andpreferable mode 'of constructing the front electrode is to cover theshelves attached to the rear electrode by a carbon or metal innermovable diaphragm or disk which sets in a case of non-conductingmaterial which surrounds the back electrode and supports the innerdiaphragm, having an outer fixed diaphragm, which may be of any suitablematerial, metal preferred, leaving a space between the outer diaphragmand the inner diaphragm or disk. The outer diaphragm is sustained by itsedges, but free to vibrate, with a fixed adjustable nut attached to itscenter with a screw passing through the fixed nut and projecting throughthis diaphragm. The screw is smooth-pointed and worked from the front ofthe transmitter by a screw-driver orotherwise, so that the point of thescrew touches the face of the inner diaphragm or disk, the result beingthat each vibration of the outer diaphragm instantaneously presses thepoint of the screw against the inner diaphragm or disk, which IOOvibrates it simultaneously with the outer diaphragm, the inner diaphragmor disk per forming the same functions as if directly acted upon by thevoice, but more effectively. This screw also acts as an adjuster.

The accompanying drawings illustrate my invention. p v

Figure 1 is a side elevation of a telephonetransmitter embodying myinvention when set up perpendicularly for commercial use. Fig. 2 is asectional View of the rear electrode, showing myinvention when theshelves are placed horizontally with a single 'dia Fig. 3 is a sectionalview of the phragm. same thing, showing my invention when the shelvesare placed circular. Figs. 4 and 5 are views of the faces of Figs. 2 and3, illustrating the two methods of arranging the shelves. of Fig. 1,showing my invention when I use horizontal shelves and asinglediaphragm. Fig. 7 is the same showing the circular shelves. Fig. 8 showsthe same when I use an inner and outer diaphragm and shows the adjusting device. Fig. '9 is the same as Fig. 2-, showing its constructionwhen I use a noncon'ductin'g diaphragm. 4

I will describe my'in'yention as illustrated.

"0. and a are the two parts of the ome case, which ma be of metal,glass, wood, hard rub her, or other composition. I prefer it made ofnon-conducting material, because if made of metalit requires a lining ofnon-conducting material. a p I 'Z; is the usual mouthpiece into whichthe user speaks.

c is the outer diaphragm, and c is the inne'r "diaphragm. Either'or bothcan bemade of metal or hard carbon or other suitable m-aterial. Y

dis the metal ring or plate to which the diaphragm c is attached whenonly one diaphragm is used, and when the outer dia'*-.

phragm c is not used forms the front electro'd'e from which contact istaken.

I Cl is the front electrode when the outer diaph'ragm cis used, andcontact is taken from the adjusting-nut on the outer diaphragm c.

'e is the rear electrode, which can be made I prefer the latter, or itcan be hard carbon electrotyped with metal to strengthen it,'which isfastened to a of metal or hard carbon.

by means of a screw or screws or clamp.

.f are the non-conducting vibrating shelves,

which I make of mica or any other suitable non-"conductin g material andfirmly attach to willmove flexibly and vibrate.

g is a screw which passes through the center of the electrode 6 and casea, holding them together, and from which contact can 1 be taken to h,which is the contact-post of the rear electrode, and maybe used as anadjusting-screw to move the rear electrode.

1' is the contact-post of the front electrode (Z or cl,connected bymeans of a wire running through case a.

Fig. 6 is a vertical central s ction,

j is the granulated carbon between the elec trodes.

76 is the adj listing-screw to move the inner diaphragm 0 when twodiaphragms are used.

Z is the insulation-band inclosing rear electrode e and forming the endof the horizontal shelves.

Z is the same when it covers 6 and insulates it from the metal ring 012.

m is a wide metal ring which I use in connection with and when I use anon-conduct ing diaphragm, such as wood or mica, with the horizontalshelves, which passes sufficiently over the rear electrode, separatedtherefrom by insulating material Z, such as mica or its equivalent, sothat it will allow the diaphragm which is attached to its top or frontend to come in contact with the shelves, and at the same time the insideof the metal ring forms the end of the shelves coming in contact withthe granulated car'- bonformiig the front electrode. 7 v

' Although I show the two forms of flexible shelves which I prefer, thematerial and 001m positions may be varied to ope-rate in a similarmanner for the same pujrpose in squares, diamonds, octagonal, and othershapes and at different angles. I have worked the shelves when placedfrom ten degrees to a right angleto the face of the rear electrode, butI prefer when I use circular shelves to place them at from twenty tothirty degrees to the face of the rear electrode, and when I usehori'zontalshelves to place them-at from fortyfive to fifty degrees tothe face of the rear electrode. V 7

Having described the preferable forms of my deviceand differentmodifications thereof, I do not limit myself to the particular mechanismshown or described, because I found that modified {and different formsof shelves, while not producing as good results as the two forms which Iprefer and have adopted for commercial purposes, were much better andcheaper than most of the transmitters now in use. V

The transmitter which I have described is adapted to short or longservice, according to the amount of electrical force used in connectionwith it, and they are uniform in quality of transmission.

Having described my invention, I claim and desire to secure by LettersPatent-- 1-. In a telephone-transmitter, the combination of flexible,non-conducting shelves,

I I w electrodes, and granular conducting material the face of the rearelectrode, so that they suspended on the shelves between the electrodesas described.

2. In a telephone-transmitter, the combination of flexiblenon-conducting shelves, granular conducting material thereon suspendedon the shelves between electrodes, an inner diaphragm in contact withthe shelves and the granular con ductin g material, a fixed outerdiaphragm with a space between the diaphragms and a mechanicalconnection between the diaphragms, as described.

IIO

rial thereon suspended between the electrodes, an inner diaphragm incontact with the shelves andthe granular conducting material, a fixedouter diaphragm, with a space 15 between the diaphragms and a screw andnut for regulating the pressure of the inner diaphragm against theshelves and the granular conducting material thereon, as described.

In witness whereof I have hereunto set my 20 hand and seal this 30th dayof November,

D. NOBLE ROWAN. [14. s.] Witnesses:

T. W. MOORE, WEBSTER GILLETTE.

